Pressurizable containers are well known in the art. Such containers are often used to hold and dispense consumer products, such as shaving cream, air fresheners, cleaners, furniture polish, etc. The container may be pressurized to a pressure greater than atmospheric pressure using propellants, inflatable bags, powered pumps, manual pumps such as a squeeze trigger, etc.
The contents of the container, when pressurized, may be dispensed from a nozzle or other opening juxtaposed with the top of the container. For example, the top of the container may have a neck with a threaded cap as occurs with common soft drinks, so that the contents may simply be poured from the container when the cap is removed. Alternatively, the top of the container may be provided with a nozzle so that the contents are dispensed from the container as a foam, gel, mist or spray. Various other types of dispensing mechanisms are well-known in the art.
In order to accommodate the desired pressure during shipment, storage and transport the walls of the container must be able to withstand and maintain the pressure after manufacture through a variety of temperatures, orientations, and handling by the user. The walls of the container must therefore be thick enough to prevent leakage of the contents under pressure or cracking due to stress. This has been accomplished by providing thicker walls. However, relatively thick walls present the problem of material cost and are viewed as environmentally unfriendly.
One approach to solving this problem has been to provide relatively thin side walls and a hemispherical or otherwise curved base. A hemispherical base resists pressure better than a flat base.
However, this approach provides the disadvantage that the curved base does not allow the container to sit upright on horizontal surfaces such as a shelf or table. Such a base may be considered irregular. By irregular it is meant an upright container having such a base cannot stand upright on a horizontal surface without falling over.
One attempt in the art to overcoming this problem includes fitting a base cup over the hemispherical bottom of the container. The base cup fits around the periphery of the container and has a flat bottom. The flat bottom permits the base cup, and container attached to thereto, to sit upright.
Attachment of the base cup to the bottom of the container has presented yet its own problems. Various groove/projection systems have been proposed for the attachment. The groove/projection systems typically provide a circumferential groove and complementary projection around the container. The groove projection system is typically disposed near the curved bottom of the container, such as the point of tangency between the curved bottom and side wall of the container. The base cup is a complementary projection or groove, which engages the groove or projection of the container. Such engagement provides a mechanical fit which prevents separation of the base cup from the container during ordinary use.
The container with the engagement system must pass regulatory drop tests to ensure safety during handling and shipment. The engagement system must be robust enough to provide both static and dynamic attachment between the container and base cup.
However, such engagement systems present their own problems. The interface between the projection and groove is not always smooth. This results in a noticeable line or ridge, which is unsightly. This effect is exacerbated, if shrink wrap or other labeling is placed around the container. The unsightly line or ridge may appear even more pronounced as one tries to hide it.
This problem may be exacerbated when the container is pressurized. The line between the base cup and container may appear less pronounced under atmospheric conditions. However, when the container is pressurized, expansion may occur. Such expansion may cause further mismatch at the interface between the mating edges of the container and base cup.
One attempt to solve this problem has been to adhesively attach the base cup to the container. This approach provides the disadvantage that an additional material cost in the form of the adhesive occurs. Additionally, an extra manufacturing step has to occur between the manufacture of the container and the attachment of the base cup thereto. The adhesive has to be applied to either or both of the container and base cup, requiring an additional operation and extra machinery.
Yet other problems occur when the container uses a dip tube to dispense contents. The dip tub may not be positioned at the lowest point of the container, allowing contents to be wasted. For example, if a hemispherical-bottom container is held at an angle, the bottom of the dip tube may not be immersed in the contents of the container. One approach to solving this problem has been place a well in the bottom of the container. However, this approach may not be feasible with a container having a hemispherical bottom designed to withstand internal pressure.
Accordingly, there is a need to solve the problems of providing a thin walled container, a container which can sit on a horizontal surface, a container that can sit on a horizontal surface utilizing a base cup, the utilization of a base cup without the need for adhesive attachment, and to have a base cup which mechanically engages in the container without the appearance of an unsightly line at the interface between the container and base cup.